WO2014046063A1

WO2014046063A1 - Curved tube structure and die for forming curved tube

Info

Publication number: WO2014046063A1
Application number: PCT/JP2013/074933
Authority: WO
Inventors: 洋平相馬; 中谷　浩之; 義夫友野; 忠広北村; 義行後藤
Original assignee: 株式会社ニフコ
Priority date: 2012-09-18
Filing date: 2013-09-13
Publication date: 2014-03-27
Also published as: JP5969617B2; EP2899445B1; US10253913B2; KR20140036965A; JP2016194370A; JPWO2014046063A1; CN106382430A; US20150226360A1; MX2015003482A; CN106382430B; CN104620037B; WO2014046063A8; MX368581B; CN104620037A; JP6388620B2; EP2899445A4; EP2899445A1; KR20150044025A; KR101713477B1; KR20160023757A

Abstract

The tube main body (12) of a curved tube (10) has a flow path following the axis line (12A), and has a curved section (14) in one portion of the direction along the axis line (12A). Further, in the inner periphery (14A) on the inside of the curve direction of the curved section (14) in the tube main body (12), a depression (16) is formed as an expanded cross-section portion along the direction of the axis line (12A). Further, in the inner die of the die for forming the curved tube, a hinge core forming the depression is inserted in a groove of the main core, and by the main core moving towards a retracted position, the tip of the hinge core, which has a shape that engages the inner periphery (14A) on the inside of the curve direction of the curved section (14), swings towards the formation position of the main core.

Description

Curved pipe structure and curved pipe mold

The present invention relates to a bent pipe structure and a bent pipe forming die applied to a bent portion of a pipe constituting a fluid flow path.

Conventionally, there are, for example, Patent Documents 1 and 2 as bent pipes applied to bent portions of pipes constituting fluid flow paths. In patent document 1, it is set as the structure with few pressure losses (head loss) by improving the water supply pipe insertion stopper protrusion inside the internal peripheral surface of a bending part into R shape. Further, in Patent Document 2, the swing member retreats and swings from the molding position to the inward retract position by the undercut portion when the main core of the inner mold is pulled out, and the slide member is molded by the undercut portion. It slides out to the inward retracted position. The main core can be pulled out of the curved pipe by the retraction swing of the swing member and the retraction slide of the sliding member.

JP 2010-64472 A JP 2009-285905 A

The present invention provides a curved pipe structure and a curved pipe molding die that can be applied to a small-diameter curved pipe and can reduce pressure loss of fluid.

According to a first aspect of the present invention, a tube main body having a bent portion in a part in the axial direction, and an inner inner periphery of the bent portion along the axial direction of the tube main body, There is provided a curved pipe structure having a cross-sectional area enlarged portion for enlarging a cross-sectional area.

In the above aspect, the cross-sectional area enlarged portion for enlarging the cross-sectional area of the tube main body along the axial direction of the tube main body is formed on the inner periphery of the bent portion of the tube main body in the bending direction. For this reason, when the fluid passes through the inside of the bent portion of the tube body, the pressure loss of the fluid can be reduced by the cross-sectional area enlarged portion. In addition, since the cross-sectional area enlarged portion is formed along the axial direction of the tube main body on the inner periphery of the bent portion in the bending direction, the structure of the mold is simplified and it can be applied to a small-diameter bent tube.

According to a second aspect of the present invention, in the first aspect of the present invention, the cross-sectional area enlarged portion has a shape as viewed from the axial direction, and both side wall portions and a bottom surface are arcs convex toward the outer peripheral side of the tube body. It may be a concave portion.

In the above aspect, the shape of the cross-sectional area enlarged portion viewed from the axial direction is a concave portion in which both side wall portions and the bottom surface are arcs convex toward the outer peripheral side of the tube body. For this reason, the channel cross-sectional area of the bent portion can be increased. As a result, the pressure loss of the fluid can be reduced.

The third aspect of the present invention may be an arc in which the both side wall portions and the bottom surface are smoothly connected in the second aspect of the present invention.

In the above embodiment, both side wall portions and the bottom surface are circularly connected smoothly. This simplifies the mold structure.

The fourth aspect of the present invention may be an arc in which the boundary between the both side wall portions and the bottom surface is bent in the second aspect of the present invention.

In the above aspect, the boundary between the side wall portions and the bottom surface is a curved arc. For this reason, the channel cross-sectional area of the bent portion can be increased. As a result, the pressure loss of the fluid can be reduced.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the cross-sectional area enlarged portion has a shape when viewed from the axial direction, the side wall portions are straight, and the bottom surface is toward the outer peripheral side of the tube body. It may be a concave portion that is a convex arc.

In the above aspect, the shape of the cross-sectional area enlarged portion viewed from the axial direction is a concave portion in which both side wall portions are straight and the bottom surface is a convex arc toward the outer peripheral side of the tube body. For this reason, the channel cross-sectional area of the bent portion can be increased. As a result, the pressure loss of the fluid can be reduced.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the cross-sectional area enlarged portion may be a concave portion whose side wall portions and bottom surface are straight when viewed from the axial direction. Good.

In the above aspect, the shape of the cross-sectional area enlarged portion viewed from the axial direction is a concave portion in which both side wall portions and the bottom surface are straight. This simplifies the mold structure.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects of the present invention, the bottom surface of the concave portion protrudes toward the axial line side when the concave portion is viewed from a side perpendicular to the axial direction. It may be a curved surface.

In the above aspect, the bottom surface of the concave portion is a curved surface convex toward the axial line side when the concave portion is viewed from the side perpendicular to the axial direction. For this reason, the flow path becomes smooth and the pressure loss of the fluid can be reduced.

According to an eighth aspect of the present invention, in any one of the first to sixth aspects of the present invention, the bottom surface of the concave portion is an inclined surface when the concave portion is viewed from a side perpendicular to the axial direction. May be.

In the above aspect, since the bottom surface of the recess is an inclined surface when the recess is viewed from the side perpendicular to the axial direction, the structure of the mold can be simplified.

A ninth aspect of the present invention has a cross-sectional area enlarging portion that is formed along the axial direction on the inner periphery of the bending portion provided in a part of the axial direction, and extends along the axial direction. An inner mold that molds the inner peripheral surface of the tube main body, and an outer mold that molds the outer peripheral surface of the tube main body, and the inner mold is pulled apart and moved in the axial direction of the tube main body. A pair of main cores that can be separated and combined with each other in the axial direction, and a pair of main cores inserted into a groove formed along the axial direction in at least one of the pair of main cores. At least one of the pair of main cores is movable between the molding position and the retracted position, and at least one of the pair of main cores moves in the retracted position direction, thereby engaging the inner periphery of the bent portion in the bending direction. The pair of main cores is the tip of the mating shape Providing curved pipe mold having a secondary core swings to at least one of the molding position.

In the above aspect, the tube main body having the cross-sectional area enlarged portion formed to enlarge the cross-sectional area of the pipe main body along the axial direction on the inner periphery in the bending direction of the bending portion is formed by the outer mold and the inner mold. Then, the outer mold is removed and the inner mold and the pipe body are separated. At this time, the pair of main cores of the inner mold are separated and each moves toward the retracted position. In addition, the main core moves along the axial direction from the molding position to the retracted position along the groove portion with respect to the sub-core inserted into the groove portion formed along the axial direction in at least one of the pair of main cores. . Along with the movement of the main core, the tip end portion of the sub-core engaged with the inner periphery of the bending portion in the bending direction swings to the main core molding position where the main core moves to become a space. For this reason, an inner metal mold | die can be extracted easily from a pipe | tube main body. Moreover, it is set as the inner metal mold | die of the structure which inserts a subcore in the cross-sectional area expansion part formed along an axial direction in the bending direction inner side inner periphery of a bending part. For this reason, the structure of the inner mold is simplified. As a result, it can be applied to a small-diameter curved pipe. Further, in the molded tube main body, the pressure loss of the fluid can be reduced by the cross-sectional area enlarged portion formed along the axial direction on the inner periphery of the bent portion in the bending direction.

Since the first aspect of the present invention has the above configuration, it can be applied to a small-diameter curved pipe and can reduce the pressure loss of the fluid.

Since the second aspect of the present invention has the above configuration, the pressure loss of the fluid can be reduced.

Since the third aspect of the present invention is configured as described above, the structure of the mold can be simplified.

Since the fourth aspect of the present invention has the above configuration, the pressure loss of the fluid can be reduced.

Since the fifth aspect of the present invention has the above configuration, the pressure loss of the fluid can be reduced.

Since the sixth aspect of the present invention is configured as described above, the structure of the mold can be simplified.

Since the seventh aspect of the present invention is configured as described above, the pressure loss of the fluid can be reduced.

Since the eighth aspect of the present invention is configured as described above, the structure of the mold can be simplified.

Since the curved pipe molding die of the present invention according to claim 9 has the above-mentioned configuration, it can be applied to a small-diameter curved pipe and can reduce the pressure loss of fluid.

It is the perspective view which made the cross section which looked at the part which shows the curved pipe structure which concerns on 1st Embodiment of this invention from the side orthogonal to an axial direction. It is a perspective view which shows the curved pipe structure which concerns on 1st Embodiment of this invention. FIG. 3 is an enlarged cross-sectional view taken along a line 3-3 in FIG. 2. It is the perspective view seen from the front end side which shows the inner mold of the metal mold | die for curved pipe shaping | molding which concerns on 1st Embodiment of this invention. It is the perspective view seen from the anti-tip side which shows a part of inner metal mold | die of the bending pipe molding metal mold | die which concerns on 1st Embodiment of this invention. It is sectional drawing along the axial direction of the curved pipe which shows the molding position of the metal mold | die for curved pipe shaping | molding which concerns on 1st Embodiment of this invention. It is sectional drawing along the axial direction of the curved pipe which shows the mold release middle of the metal mold | die for curved pipe forming which concerns on 1st Embodiment of this invention. It is sectional drawing along the axial direction of the curved pipe which shows the mold release middle part following FIG. 7 of the metal mold | die for curved pipe forming which concerns on 1st Embodiment of this invention. It is a perspective view corresponding to Drawing 1 showing the curved pipe structure concerning a 2nd embodiment of the present invention. It is sectional drawing corresponding to FIG. 3 which shows the curved pipe structure which concerns on 2nd Embodiment of this invention. It is the perspective view seen from the front end side which shows the inner mold of the metal mold | die for curved pipe shaping | molding which concerns on 2nd Embodiment of this invention. It is the perspective view seen from the other end side which shows a part of inner mold of the metal mold | die for curved pipe shaping | molding which concerns on 2nd Embodiment of this invention. It is a perspective view corresponding to FIG. 1 which shows the curved pipe structure which concerns on 3rd Embodiment of this invention. It is sectional drawing corresponding to FIG. 3 which shows the curved pipe structure which concerns on 3rd Embodiment of this invention. It is the perspective view seen from the front end side which shows the inner metal mold | die of the bending pipe molding metal mold | die which concerns on 3rd Embodiment of this invention. It is sectional drawing corresponding to FIG. 3 which shows the curved pipe structure which concerns on 4th Embodiment of this invention. It is a perspective view corresponding to FIG. 1 which shows the curved pipe structure which concerns on 5th Embodiment of this invention. It is sectional drawing along the axial direction of the curved pipe which shows the curved pipe structure which concerns on 6th Embodiment of this invention. It is sectional drawing along the axial direction of the curved pipe which shows the curved pipe structure which concerns on 7th Embodiment of this invention. It is sectional drawing along the axial direction of the curved pipe which shows the curved pipe structure which concerns on 8th Embodiment of this invention. It is sectional drawing along the axial direction of the curved pipe which shows the shaping | molding position of the metal mold | die for curved pipe shaping | molding concerning 9th Embodiment of this invention. It is sectional drawing along the axial direction of the curved pipe which shows the mold release middle of the metal mold | die for curved pipe shaping | molding concerning 9th Embodiment of this invention. It is a perspective view corresponding to FIG. 1 which shows the curved pipe structure which concerns on a prior art example. It is sectional drawing corresponding to FIG. 3 which shows the curved pipe structure which concerns on a prior art example.

Next, a curved pipe structure and a curved pipe forming mold according to a first embodiment of the present invention will be described with reference to FIGS.
In the drawings, members (components) having the same or corresponding functions are denoted by the same reference numerals and description thereof is omitted as appropriate.

(Curved pipe structure)
As shown in FIG. 2, the tube main body 12 of the curved tube 10 of the present embodiment has a flow path having a circular cross section along the axis 12 A and is bent substantially perpendicularly to a part of the direction along the axis 12. Part 14. Moreover, the both ends 12B of the pipe | tube main body 12 are opened, and the hose 15 is connected with each both ends 12B as an example.

As shown in FIG. 1, a concave portion 16 as a cross-sectional area enlarged portion is formed along the direction of the axis 12 A on the inner inner periphery 14 A of the bent portion 14 in the bending direction. The area is expanding. Accordingly, when a fluid such as a liquid (arrow W in FIG. 1) passes through the bent portion 14, the concave portion 16 can reduce the pressure loss of the fluid.

As shown in FIG. 3, the recess 16 is formed on the inner periphery 14A in the bending direction of the bent portion 14 indicated by a two-dot chain line. Further, the recess 16 has a shape seen from the direction of the axis 12 A (a shape seen from the direction along the axis 12 A), and both side wall portions 16 B and the bottom surface 16 A are arcs convex toward the outer peripheral side of the tube body 12. Therefore, as in the conventional example shown in FIG. 23 and FIG. 24, compared with the tube body 102 that does not form the cross-sectional area enlarged portion on the inner periphery 104 in the bending direction of the bending portion 104, The cross-sectional area S of the bent portion 14 is large. In the present embodiment, the side wall portions 16B and the bottom surface 16A are circular arcs that are smoothly connected.

Next, the operation of this embodiment will be described.
In the tube main body 12 of this embodiment, when a fluid such as a liquid (arrow W in FIG. 1) passes through the bent portion 14, the pressure loss of the fluid can be reduced by the recess 16. In addition, since the concave portion 16 is formed along the direction of the axis 12A on the inner periphery 14A in the bending direction of the bending portion 14, the structure of the mold is simplified, and a small-diameter bent tube (for example, an inner diameter of 40 mm or less) is formed. (Curved pipe).

Further, in the present embodiment, the shape of the concave portion 16 viewed from the direction of the axis 12A of the both side wall portions 16B and the bottom surface 16A is a circular arc convex toward the outer peripheral side of the tube body 12, and the both side wall portions 16B and the bottom surface 16A are smooth. It is an arc connected to. For this reason, the structure of the mold can be further simplified.

(Mold for pipe bending)
As shown in FIG. 6, the bent pipe forming mold 20 of the present embodiment includes an outer mold 22 and an inner mold 24. The outer mold 22 has a two-part divided mold structure, and forms an outer peripheral surface of a synthetic resin tube main body 12 to be molded by injection molding. On the other hand, the inner mold 24 is configured to mold the inner peripheral surface of the pipe body 12. The inner mold 24 has a pair of main cores 30 having the same shape and a hinge core 34 (sub core) as a pair of sub cores having the same shape. Each main core 30 and each hinge core 34 are elongated along the direction of the axis 12 A of the tube body 12. Each main core 30 and each hinge core 34 are separated from each other in the direction of the axis 12A at the center of the bent portion 14 in the direction of the axis 12A by pulling away and approaching in the direction of the axis 12A of the tube body 12. Can be merged.

As shown in FIGS. 4 and 5, a groove portion 32 is formed along the direction of the axis 12 A of the tube body 12 at a portion corresponding to the inner circumference 14 A of the bending portion 14 in each main core 30. . For this reason, the distal end portion 30 A of each main core 30 has a shape that does not engage with the undercut portion of the inner periphery 14 A (concave portion 16) in the bending direction of the bending portion 14 of the tube body 12.

Each hinge core 34 is inserted into the groove portion 32 of each main core 30 so as to be slidable relative to the main core 30 along the direction of the axis 12A of the pipe body 12. The inner peripheral surface of the tube body 12 is formed by a curved molding surface 30B of the main core 30 and a curved molding surface 34A of the hinge core 34. Each hinge core 34 has a base portion 36 on one side in the longitudinal direction and a swinging portion 38 on the other side in the longitudinal direction connected by a hinge portion 40.

As shown in FIG. 6, in the hinge portion 40 of the hinge core 34, the concave portion of the base portion 36 formed in a semicircular shape when viewed from the side orthogonal to the direction of the axis 12 A and the convex portion of the swinging portion 38 are related. Match. Then, with the axis P1 of the hinge portion 40 as the center, the swinging portion 38 approaches the axis 12A with respect to the base portion 36 (in the direction of arrow B in FIG. 4) and the direction away from the axis 12A (in FIG. 4). It swings in the direction opposite to arrow B). Moreover, the hinge part 40 incorporates the coil spring 41 as an urging means, and the oscillating part 38 approaches the axis 12A with respect to the base part 36 by the urging force of the coil spring 41 (the arrow in FIG. 4). B direction). That is, the swinging portion 38 is biased by the hinge portion 40 in the direction of arrow B in FIG. 4 and is pressed against the bottom portion of the groove portion 32.

The distal end 38A of the swinging portion 38 of each hinge core 34 corresponds to the undercut portion of the concave portion 16 formed on the inner periphery 14A in the bending direction of the bending portion 14 of the tube body 12, and is curved to engage with the concave portion 16. It has a shape.

That is, in the molding position shown in FIG. 6, the swinging portions 38 of the pair of hinge cores 34 are at positions where the tips 38 A form the concave portions 16 that are the inner perimeter 14 A in the bending direction of the bending portion 14 of the tube body 12. The swinging portions 38 of the pair of hinge cores 34 are accommodated in the groove portions 32 of the main cores 30 at the molding position.

As shown in FIG. 7, when the pair of main cores 30 are separated and moved from the molding position to the retracted position direction (in the direction of arrow A in FIG. 7), the swinging portions 38 of the hinge cores 34 are moved by the hinge portions 40. It swings in the direction of arrow B. That is, the swinging portion 38 of each hinge core 34 is moved from the molding position shown in FIG. 6 to the molding position of the main core 30 in which the main core 30 is moved as shown in FIG. It swings to the swing position).

As shown in FIG. 8, when the pair of main cores 30 further move in the retracted position direction (the direction of arrow A in FIG. 8), the engaging portions 50 formed at the tips of the groove portions 32 of the pair of main cores 30 It engages with a convex portion 52 formed on the base portion 36 of the hinge core 34. The hinge cores 34 are moved together with the pair of main cores 30 in the direction of arrow A in FIG. 8, so that the inner mold 24 is separated from the pipe body 12.

Next, the operation of this embodiment will be described.
When the tube main body 12 is formed by the bent tube forming die 20 of this embodiment, first, a synthetic resin is injected into the space formed by the outer die 22 and the inner die 24, and the recess 16 is formed. The bent tube main body 12 is formed. Thereafter, the outer mold 22 is removed and the inner mold 24 and the pipe body 12 are separated.

At this time, with respect to each hinge core 34, the pair of main cores 30 are drawn and separated from the molding position shown in FIG. 6 along the groove portion 32 in the drawing direction (direction of arrow A in FIG. 7) along the axis 12A. Further, when the pair of main cores 30 are separated and moved from the molding position toward the retracted position, the swinging portions 38 of the hinge cores 34 are moved by the hinge portions 40 and the main cores 30 are moved to spaces. It swings to the molding position of the core 30. Therefore, the swinging portion 38 of each hinge core 34 is in the swinging position shown in FIG. Next, as shown in FIG. 8, when the pair of main cores 30 are further moved in the retracted position direction (the direction of arrow A in FIG. 8), the engaging portions formed at the tips of the grooves 32 of the pair of main cores 30. 50 engages with a convex portion 52 formed on the base portion 36 of each hinge core 34. And each hinge core 34 moves to the arrow A direction of FIG. 8 with a pair of main core 30, respectively, and the inner metal mold | die 24 can be extracted from the pipe body 12 without difficulty.

That is, in the bent pipe forming mold 20 of the present embodiment, the hinge core 34 inserted into the groove part 32 of the pair of main cores 30 of the inner mold 24 causes the bent inner side 14 A of the bent part 14 of the pipe body 12 to be bent. A recess 16 is formed along the direction of the axis 12A. For this reason, the structure of the inner mold 24 of the bending pipe forming mold 20 is simplified, and the structure can be applied to a small diameter bent pipe. Further, in the molded tube main body 12, the pressure loss of the fluid can be reduced by the recess 16 formed along the axial direction on the inner circumference 14 A in the bending direction of the bending portion 14.

(Other embodiments)
Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to the first embodiment, and various other embodiments are within the scope of the present invention. It will be apparent to those skilled in the art that this is possible. For example, as in the second embodiment shown in FIGS. 9 to 12, the shape of the side wall 16B and the bottom surface 16A of the recess 16 viewed from the direction of the axis 12A is convex toward the outer peripheral side of the tube body 12, and the side walls 16B The boundary J with the bottom surface 16A may be a curved arc. Thereby, the flow-path cross-sectional area of the bending part 14 of the pipe | tube main body 12 can be enlarged. As a result, the pressure loss of the fluid can be reduced. There may be two or more bent borders J.

Further, as in the third embodiment shown in FIGS. 13 to 15, the shape of the concave portion 16 viewed from the direction of the axis 12A is such that both side wall portions 16B are straight lines along the swinging direction of the hinge core 34, and the bottom surface 16A is the tube body. It is good also as a 12 circular arc convex to the outer peripheral side. Thereby, the flow-path cross-sectional area of the bending part 14 of the pipe | tube main body 12 can be enlarged. As a result, the pressure loss of the fluid can be reduced. Further, the bottom surface 16A of the concave portion 16 is a curved surface convex toward the axis 12A when the concave portion 16 is viewed from the side orthogonal to the direction of the axis 12A, and the flow path of the bent portion 14 is smooth. For this reason, the flow path of the bending part 14 becomes smooth and the pressure loss of the fluid can be further reduced.

Further, as in the fourth embodiment shown in FIG. 16, the shape of the recess 16 viewed from the direction of the axis 12A is such that both side wall portions 16B are straight along the swinging direction of the hinge core 34, and the bottom surface 16A is the both side wall portions 16B. It may be a straight line perpendicular to. Thereby, the structure of the hinge core 34 of the inner mold 24 can be simplified. In addition, the shape seen from the axis 12A direction of the recessed part 16 is not limited to the shape of each said embodiment, It is good also as another shape.

Also, as in the fifth embodiment shown in FIG. 17, the bottom surface 16A of the recess 16 may be an inclined surface when the recess 16 is viewed from the side perpendicular to the direction of the axis 12A. Thereby, the structure of the hinge core 34 of the inner mold 24 can be simplified. In addition, the shape seen from the side orthogonal to the direction of the axis 12A of the recessed part 16 is not limited to the shape of each said embodiment, It is good also as another shape.

Further, in each of the above-described embodiments, the main core in which the main core 30 is moved into the space by the urging means 38 such as the coil spring 41 built in the hinge portion 40 of the hinge core 34 as the sub core is moved. It was configured to swing to 30 molding positions (swing position of the swinging portion 38). Instead, the hinge part itself is elastically deformed, so that the main core 30 moves into the space by moving the main part 30 in the swing part 38 (swing position of the swing part 38). It is good also as composition to do.

In each of the embodiments, the curved pipe structure and the curved pipe forming die of the present invention are applied to a curved pipe having a bent portion 14 that is bent substantially perpendicularly to a part of the direction of the axis 12A. The bent pipe structure and the bent pipe forming mold of the invention can be applied to other bent pipes. For example, as in the sixth embodiment shown in FIG. 18, the present invention can also be applied to a curved pipe having a T-shaped bent portion 14 in a part in the axial direction of the pipe body 12. Moreover, it is applicable also to the curved pipe which has the Y-shaped bending part 14 in a part of axial direction of the pipe main body 12 like 7th Embodiment shown in FIG. Further, as in the eighth embodiment shown in FIG. 20, the present invention can also be applied to a curved pipe having an X-shaped bent portion 14 in a part of the pipe body 12 in the axial direction.

In each of the above embodiments, the inner mold 24 is configured to include a pair of main cores 30 having the same shape and having a hinge core 34 as a sub-core. Instead, as in the ninth embodiment shown in FIGS. 21 and 22, the inner mold 24 includes a main core 30 having a hinge core 34 as a sub core, and a main core 60 having no sub core. It is good also as a structure provided. In this embodiment, the tip 38A of the swinging portion 38 of one hinge core 34 corresponds to the undercut portion of the entire recess 16 formed on the inner periphery 14A in the bending direction of the bending portion 14 of the tube body 12. Further, the tip 38 A of the swinging portion 38 has a curved shape that engages the entire area of the recess 16.

Claims

A tube body having a bent portion in a part in the axial direction;
A cross-sectional area enlarged portion for enlarging the cross-sectional area of the tube body, formed along the axial direction of the tube body on the inner periphery of the bent portion in the bending direction;
Have
2. The bent pipe structure according to claim 1, wherein the cross-sectional area enlarged portion is a concave portion having a shape seen from the axial direction, wherein both side wall portions and a bottom surface are convex arcs toward the outer peripheral side of the tube main body.
The curved pipe structure according to claim 2, wherein the both side wall portions and the bottom surface are circular arcs smoothly connected.
The curved pipe structure according to claim 2, wherein the boundary between the side wall portions and the bottom surface is a curved arc.
2. The curved pipe according to claim 1, wherein the cross-sectional area enlarged portion is a concave portion in which the shape seen from the axial direction is a straight wall on both side walls and a bottom surface is an arc convex toward the outer peripheral side of the pipe body. Construction.
2. The curved pipe structure according to claim 1, wherein the cross-sectional area enlarged portion is a concave portion in which the shape seen from the axial direction is a straight line on both side walls and the bottom surface.
The curved pipe structure according to any one of claims 1 to 6, wherein the bottom surface of the concave portion is a curved surface convex toward the axial line side when the concave portion is viewed from a side perpendicular to the axial direction.
The curved pipe structure according to any one of claims 1 to 6, wherein a bottom surface of the concave portion is an inclined surface when the concave portion is viewed from a side perpendicular to the axial direction.
An inner peripheral surface of a pipe body having a cross-sectional area enlarged portion for enlarging a cross-sectional area is formed on the inner inner circumference in the bending direction of a bent portion provided in a part of the axial direction, and is formed along the axial direction. With inner mold,
An outer mold for molding the outer peripheral surface of the tube body;
With
The inner mold is
A pair of main cores that can be separated and combined with each other in the axial direction by pulling away and approaching in the axial direction of the tube body;
At least one of the pair of main cores is inserted into a groove formed along the axial direction, and at least one of the pair of main cores is relatively movable between the molding position and the retracted position along the groove. In addition, at least one of the pair of main cores moves in the retracted position direction, so that a tip portion of the shape that engages with the inner periphery of the bending portion in the bending direction is formed of at least one of the pair of main cores. A secondary core that swings into position,
A mold for forming a bent pipe.